# The isBadVersion API is already defined for you.
# def isBadVersion(version: int) -> bool:

class Solution:
    def firstBadVersion(self, n: int) -> int:
        left=1
        right=n
        while left < right:
            mid = (left+right)//2
            if isBadVersion(mid):
                right=mid
            else:left=mid+1
        return right
            

